Recording and reproduction of alternating impulses



s- 4, 1942- s. DIMMICK 2,292,062

RECORDING AND REPRODUCTION OF ALTERNATING I MPULSES Filed July 29, 1959 :s Sheets-Sheet 1 .FfrG. 2a.

IIIHII II I ll anus 2- II I! RED RED I I I ll 5 I III 1m am 5- Snuentor Glenn L. Dim mic/i I Gttorncg 8- G. L. DIMMICK $292,062

RECORDING AND REPRODUCTION OF ALTERNATING IMPULSES .Fild July 29, 1959 5 Sheets-Sheet 3 Ham? a; 1 56.625. 1 50.60,

i- ;lmllllllliiiii 42 Snpcntor Glenn L.Dzmml,cfi

Patented Aug. 4, 1942 RECORDING AND REPRODUCTION OF ALTEINATING mosses Glenn L. Diminick, Baddonfleld, N. 8., aaaignor to Radio Corporation at America. a corporation oi Delaware Application July so. use, Serial m. zsmzs 12 Claims. '(cl. res-ms) This invention relates to the recording and reproduction oi alternating impulses such as th'ose oi audio frequency, and has ior its principal obiect the provision oi an improved record and improved means for. recording and playing or reproducing the improved record.

The invention is in some respects an improvement over those disclosed by United States Patent 2,102,696 oi Giesking and by application Berial No. 196,554 of Hullegard, both assigned to the same assignee as the present application. As will appear. all three oi these inventions involve recording in" diiierent colors the positive and negative hali cycles oi a sound wave or other alternating impulse. One suitable recording material ior this purpose is the multi-color motion picture iilm currently sold under thetrade-name oi "Kodachrome."

In the record of the aioresaid Giesking patent. the impulses are recorded in the tom positive and negative hali cycles which are diflerently colored and extend irom bases at opposite sides oi the record to peaks which overlap at the center 01 the record. -'Ihis type oi record has the disadvantage that the cross-over points between .the hali cycles are located at opposite ends oi the light beam and distortion oi the reprooutput, ior the reason that the output is balanced ior only one band of light waves. Thus, whenever the exciter lamp is replaced or whenever the heating current 01 the lamp is changed. the reproduced impulses may be distorted.

In one modification oi the present invention, this diiliculty is avoided by recording the corresponding hali cycles oi the diflerent record tracks in diiierent colors. Thus ii the negative hali cycles oi one track are blue, ior example, the negative h'ali cycles oi the other record track are oi a diiierent color. such as red. Likewise, the positive hali cycles oi the two record tracks are oi diiierent colors. This iorm oi the improved record thereiore includes a pair oi duplicate record tracks each of which has diiierently colored positive and negative hali cycles. the corresponding hali cycles oi the two tracks being oi (iiiduced impulses may result from diflerent 1mm intensities at the two ends oi the beam or irom m salignment oi the beam.

The record oi the copending Hullegard application involvesduplicate record tracks on which the corresponding negative hali cycles are recorded in one color and the corresponding posiirom transparent spots produced in the background area by scratches or the like is balanced out or neutralized in the reproducer.

The duplicate tracks oi the Hullegard record have their corresponding hali cycles recorded in the same color. and any change in the color oi the light transmitted through the record thereiore tends to unbalance the reproducer output and produce distortion in the reproduced impulses. Standardization oi the color oi the light emanated by an incandescent exciter lamp is hardly ieasible under present conditions. In the absence oi such standardization, the impulses reproduced from the Hullegard type oi record may be distorted due to unbalance oi the reproducer ierent color. As will appear, this record is oi a type commonly known as a class B record.

Since the corresponding hali cycles oi the two record tracksare oi diiierent color, the unbalancing eii'ect oi change in the color oi the exciter light source is avoided and the exclter lamp may be replaced or its heating current varied without the necessity oi readjustment oi the reproducer. A class B type oi record is one whereon the positive and negative hali cycle record areas are so disposed as to separately and alternately aiiect a pair oi push-pull connected photoelectric elements. A class A type of record is one wherein the positive and negative hali cycle record areas are so disposed as to simultaneously aiiect a pair oi push-pull connected photoelectric elements. In the case oi either record, the positive and negative hali cycle record areas arranged to separately or simultaneously aii'ect the pushpull photoelectric elements may be on the same or diilerent record tracks, the selection oi the hali cycle record areas being eiiected geometrically,.by color, by carrier frequency, by polarination, or the like.

Color separation, ior example, involves th I employment of two reproducing elements, one oi which is aflected only by light oi a certain color, and the other oi which is aiiected only by light of another color. The sound track includes diiierently stained areas which will respectively absorb light of the two different colors. For example. the reproducing elements may be two photocells and two complementary color illters such as red and blue in iront oi the first and second cells, respectively, and the sound track may be recorded by the application oi red and blue dyes or stains, each of which absorbs light oi its complementary color, but comparatively little light oi its own color. Thus the photocell having the red filter receives light which is strongly modulated by the presence oi blue dye inthe sound track but is relatively little afiected by the persence of red dye in the sound track.

While the invention is disclosed in connection with color separation, it is obviously useful in connection with other means of selecting and utilizing the various positive and negative half cycle areas of the record, it being only necessary that the corresponding half cycles be depicted on the record as modulating carriers of diiferent wave lengths, whether the carriers be differently colored light, difierently polarized light beams, different radio frequency carriers, or the like.

The invention will be better understood from the following description considered in connection with the accompanying drawings, and its scope is indicated by the appended claims.

Referring to the drawings, Figure l diagrammatically illustrates a device suitable for recording alternating impulses in the form of duplicate record tracks with their corresponding half cycles of different colors,

Figure 2a. illustrates the prior art record of Hullegard whereon the corresponding half cycles of the different tracks are depicted in the same color,

Figure 2b illustrates theclass B type of record produced by the device of Fig. 1,

Figures 3 and 4 are, respectively, top and side views of a device suitable for reproducing the impulses recorded on the record of Fig. 2b,

Figure 4a illustrates certain details of thereprcducer oi Figs. 3 and 4,

Figure 5 illustrates a modified form of reproducer,

Figure 6 is an explanatory diagram relating to the operation of the reproducer of Fig. 5,

, Figure 7 diagrammatically illustrates a device suitable for producing a class A type of record wherein two sets of duplicate record tracks, 180 degrees out ofphase with one another, are recorded in difierent colors and in alignment with one another along the boundary be- Vibration of the varicolored image across the light slit l9 produces two record tracks such as tween opaque and transparent background' areas of the record,

Figures 8a and 8d respectively illustrate the varicolord light beam of the class A record produced by the device of Fig. 7,

Figure 8b illustrates a modified form of light beam which may be utilized to produce the class A type of record shown by Fig. 8e, and

Figure 80 illustrates a further modified light beam and noise reduction shutter arrangement which may be utilized to produce the class A type of record shown by Figure 8).

The recorder of Fig. 1 includes a source In from which light passes through a lens II, the aperture of a plate I! and lenses l4 andli to a galvanometer mirror 16 which is vibrated in accordance with the electrical impulses supplied to the galvanometer operating coil l'l. From the mirror IS, an image oi the aperture of the plate I! is reflected through the lens IE to the member l8, across the light slit I! of which the aperture image is vibrated by movement of the mirror IS.

The light thus modulated passes from the slit those of Fig. 2b. This is a class B type or record and differs from the Hullegard class B record, which is shown in Fig. 2a, in that the corresponding half cycles of the record tracks are differently colored. As previously indicated, the record of Fig. 2b is superior to the prior art record of Fig. 2a in that the corresponding hall cycles are of different colors and the reproduced impulses are substantially unafiected by variation in the color of the light or the exciter lamn.

The improved record of Fig. 21) may be played or reproduced by the reproducer of Figs. 3, 4 and 4a.

This reproducer includes an exciter light source 25, which may be of the incandescent type and functions to transmit light through'an optical system, the record 22, a cylindrical lens 21 and light splitting lenses 28 to a half silvered mirror 29 or other suitable means adapted to simultaneously transmit and reflect the incident light.

Light is transmitted through the mirror 29 and the red filter 30 or a blue filter 3| to the cathode 32 of one of a pair of push-pull connected photoelectric elements 33. Light is'reflected from the mirror 28 to a mirror ll from whence it is reflected through a blue filter 35 or a red filter 36 to the cathode 31 of the other of the push-pull connected photoelectric elements. The output of the push-pull circuit is delivered through a. transformer 38 and a suitable amplifying channel to the loudspeaker or other repro- Thus each photoelectric element is subjected to half cycle areas which are difl'erently colored, and the distortion otherwise resulting from change in the color of the scanning exciter light beam is avoided.

The invention is not restricted to Class B type records, such as that of Fig. 2b, but is equally applicable to class A type records such as those illustrated by Figs. 8d, 8e and 81. Which of these three different class A types of record is produced, of course, depends on the coloring of the difierent aperture sections of the plate l2.

Thus if these aperture sections are colored as indicated by the legends applied to Fig. 7, the

lightbeam appearing at the light slit member II is colored as indicated by the legends of Fig. 8a and the record of Fig. M is produced. It will be observed (1) that this record includes two pairs of record tracks, each of which consists of duplicate records recorded in different colors and in opposition or with a phase difference of degrees, (2) that the record background areas 40 and M are opaque, and (3) that the record background area 42 is transparent.

Either one or both of the class A ype tracks of the record of Fig. 8d may be reproduced by the reproducer of Fig. 5, wherein light modulated by the record 43 passes through a lens 44 to a color separating prism 45 which directs the diflferently modulated light component to the difierent pilotoelectric elements of the device 33.

The aperture sections of the plate I2 mayalso nally of said record.

be arranged to produce a varicolored light beam such as that of Fig. 8b'or that of Fig. 8c.

Vibration of the beam of Fig. 8b across the light slit i9 produces a class A type of record such as that of Fig. 8e, which is similar to that.

is similar to those of Fig. 8d and Fig. Be in that it includes a class A type of record track recorded along the boundary between opaque and transparent background areas, is similar to the record of Fig. 8e in that the corresponding half cycles of the two class A tracks are differently colored, and diilers from the records of Figs. 8d and 8c in that the shutters 46 and 41 are oppositely moved in accordance with the volume or level of the recorded impulses to produce noise reduction record areas 4! and 49 in the manner disclosed by McDowell Patent, 1,855,l97 and numerous other prior art disclosures.

The records of Figs. 8e and 8 may be reprodliced by the reproducer of Figs. 3, 4 and 4a.

Although the colors of the record have been described as red and blue, it is obvious that any two separate bands of frequencies may be used.

The preferred method is to divide the spectrum of actinic rays into two parts, as indicated by Fig. 6. The widths of the two bands are preferably such as to produce approximately the same signal from the two push-pull connected cathodes. Under these conditions, when the repro- I 'ducer is so adjusted as to balance the currents of i of push-pull connected transversely oi said record, and on which the positive and negative half cycles of each track are recorded in alignment with one another longitudinally of said record.

6. In a device for the reproduction of alternating current impulses from a record including a plurality of record tracks having their corresponding half cycles differently colored and each having differently colored positive and negative half cycles, the combination of a plurality photoelectric elements, a

' light source, and means for causing light trans-' (initted through the corresponding positive half cycles of said tracks to be applied to one ofsaid photoelectric elements and for causing light transmitted through the corresponding negative half cycles of said tracks to be applied toanother -oi said photoelectric elements.

7. In a device for the reproduction of alternating current impulses from a record including a plurality of record tracks having their corresponding half cycles difierently colored and each having diiferently colored positive and negative half cycles, the combination of a plurality of push-pull connected photoelectric elements, a light source, and meansincluding groups of differently colored filters arranged in reverse order the two photoelectric elements, change in the color of the light emanating from the exciter lamp does not unbalance the output of the reproducer. i

' I claim as my invention:

1. An alternating current record including 7 opaque and transparent background areas having a boundary therebetween, positive half cycle record tracks of said current in one color along the said boundary between said backgrounds,.and

negativehalf cycle record tracks of said curren in a diflerent color along said boundary.

2. An alternating current impulse record including a plurality of record tracks onwhich the corresponding half cycles of said current are recorded in difierent colors. .3. An alternating current impulse record in cluding a plurality of record tracks on which the corresponding half cycles of said current are recorded in diiierent colors, and on which said corresponding half cycles are recorded in alignment with one another transversely oi said record.

4.A n alternating current impulse record in-. eluding a plurality of record tracks on which the corresponding half cycles of said current are recorded in diiierent colors, and on which the noncorresponding half cycles or each track are recorded in alignment with one another longitudi- 5. An alternating current record including a plurality of record tracks on which correspond-, ing half cycles of said current are recorded in diflerent colors in alignment with one another for'causing light from only corresponding half cycles of said tracks to be'applied to each of said photoelectric elements.

8. In a device for the reproduction of alternating current impulses from a record whereon the positive and negative half cycles are recorded in difierent colors at the boundary line between opaque and transparent background areas, the combination of a light source, a pair of pushepull connected photoelectric elements, and means for causing substantially all light transmitted through one colored area of said record to be ap-- plied to one of said elements and substantially all light transmitted through a difierently colored area of said record to be applied to the other of said elements. l

9. In a device for the reproduction of alternating current impulses from a record whereon the positive and negative half cycles are recorded in difierent colors at the boundary line between opaque and transparent background areas, the combination of a light source, a pair of push-pull connected photoelectric elements, and means in cluding a prismfor causing substantially all light transmitted through one colored area of said record to be applied to one of said elements and substantially all light transmitted through a differently colored area of said record to be applied to the otherof said elements.

10. An alternating current impulse record including a plurality of record tracks on which corresponding half cycles of said impulses are depicted as each modulating a carrier of diflferent frequency.

11. An alternating current impulse record including a plurality of record tracks on which corresponding half cycles of said impulses are, depicted as each modulating light of a difierent character. v x

12. An alternating current impulse record includlng a plurality of record tracks on which corresponding hali cycles of said impuls es are depicted as each modulating radiation of a diflierent wave length.

" GLENN DIMMICK. 

